I am thinking of having a house built. I hate to waste water while waiting for the hot water to get to the taps. Has anyone seen or heard about running one plastic line to each bathroom and then installing a on demand water heater in each bathroom? My thinking is it would cut down on installation cost by not having to run the hot water line, at the same time saving water by not having to wait for it to run the length of the house to get to the tap. Any thoughts or ideas would be great.